Conveyors are an integral part of most food factories, providing an interface between the process and the product as they move material from one stage to the next. But because they self-evidently fit in between all those different stages of production - from raw materials handling, through processing, to packaging - their importance can often be undervalued.
"You can have lots of individual pieces of conveyor, but nobody takes responsibility for the interfaces between them," says Adrian Marshall, md of consultant Crafty Tech. "The gaps between the conveyors fall into the gap between responsibilities." Marshall is actually talking of the problems that can arise when conveyors meet other conveyors, but the same disconnect can be found between processing and packaging - different departments often with their own views on their specific conveying requirements.
The problem with the gaps highlighted by Marshall is that they can introduce misalignments if the conveyors and their speeds are specified incorrectly. "What I try to do is to point out ways of not ending up with a random jumble of product at the end," he says. Typical of Crafty Tech's solutions, for example, is the patented 'Marshalling Yard' row aligner that was originally developed to unscramble Cadbury's mini chocolate rolls. Without any recourse to sensors or machine vision systems, the aligner works by effectively creating a wave-like pattern on the conveyor that, as Marshall puts it, "gathers up the product and deposits it in the right place - like a surfer being picked up by a wave and dropped on the beach"
Faced with differing conveyor requirements across the factory, many companies have made the decision to leave it all in the hands of the conveyor manufacturers and suppliers themselves. Midlands-based conveyor manufacturer Isoma, for example, recently completed the relocation of a complete bag-in-box filling line for Arla Foods at its dairy in Ashby, Leicestershire.
Like all conveyor suppliers these days, Isoma has had to take note of the increasingly stringent hygiene standards now being applied across the food industry. Its latest response is the Trough Conveyor, which features a trough along the entire length of the conveyor to contain all spillages. Fitted with collection sumps and filters integrated into the trough at regular intervals, the conveyor keeps floors dry throughout production and packaging plants.
An optional hygiene feature is a spray-ball equipped cleaning pipe along the length of the trough for internal cleaning. One side of the trough can also be removed for trouble-free access to all sprockets and slat chains.
Chains can, of course, be a source of trouble for conveyors, particularly when they are exposed to some of the aggressive cleaning procedures used in the food industry. This is a problem that Tsubaki UK has tackled head on with its Lambda WP lube-free, water protected, drive chain. Specialist packaging machine manufacturer BWI Dawson has put this chain to impressive use on a new depalletising machine it has installed at New Zealand Milk's depot in Swindon, where imported Anchor butter in bulk is processed for retail packaging. At any one time two continuous loops of 1in pitch Lambda WP chain can be lifting up to 3t of butter - up to 120t over an eight-hour shift. After each shift, each of the four depalletising machines in use is washed down using high-pressure brine at 70°C.
"The Tsubaki chain was essential to the success of this project," says BWI Dawson project manager Andy Temple. "Our previous supplier could only offer us standard chain with external food-grade lubrication, which would have been impossible bearing in mind the wash-down conditions."
The Lambda WP chain enabled BWI Dawson to design a completely corrosion resistant machine for the first time; a characteristic also claimed by Belt Technologies Europe for its conveyor systems. Its belt conveyors come complete with frame, pulleys and belts all made from stainless steel. According to European general manager Brian Harbison, the prerequisites for hygienic design are materials free from crevices that can trap dirt, manufactured from non-corrosive materials and which are easy to clean - stainless steel, in other words. The stainless steel belt itself can be perforated or plain, up to 1000mm wide and available in a range of grades.
The hygienic advantages of stainless steel are also to the fore in the new Compact Grid conveyor belt from the Wire Belt Company. Engineered with a 70% open surface area, this mesh type belt has been designed specifically to handle smaller, delicate products, especially in high speed cooling and drying processes.
Another supplier of stainless steel belts, Sandvik Process Systems, claims its 1700SA belt grade is particularly suited to use in hygiene-critical applications. At only 0.6mm to 0.2mm thick, these belts offer conveyor manufacturers the ability to design extremely compact systems with small diameter conveyor drums.
Suppliers of plastic conveyor belts, however, have not been slow in addressing the growing demands for higher standards of hygiene in equipment design. Recently granted US Drug Administration approval for meat and poultry processing, a new plastic conveyor belt from Uni-Chains has been designed to reduce bacterial growth and allow easy access for cleaning. The M-PNB belt has no lock pins that can harbour contamination. Instead, the open hinge belt design has modules that click together for easy assembly and disassembly. Suitable for duties such as cooling lines, dewatering lines, breading lines and enrobing lines, the belt has a 12.7mm pitch available in standard belt widths from 2in to 120in.
Traditionally, white has been the colour most closely associated with hygiene, which is why most conveyor and process belts in the food industry have been made of white synthetic materials. But because the colour blue seldom occurs naturally in foodstuffs, many operators are moving to blue belts as an aid to improved hygiene. Because of the striking contrast between the colour of a blue belt and anything transported on it, any soiling and residues left on the belt will be picked up more easily and at an earlier stage, so that cleaning can be that much more effective.
One of the latest manufacturers to pick up on this move to blue is Siegling. According to marketing assistant Dave Giles, the company now offers a whole range of blue belts that cover most conveying requirements in the food industry. Elsewhere, freezing and chilling technology specialist Starfrost has also introduced a new Ashworth blue plastic conveyor to its equipment range.
A different kind of blue belt has recently been added to the Habasit range. This features a blue Habilene coating, a polymer specially modified to improve the release properties of sticky foodstuffs. Also turning blue is the company's HySAN belt coating. This is a highly oil and fat resistant PVC that can operate over a temperature range from -10°C to 90°C.
Habasit also manufactures belts that contain an antimicrobial additive that helps prevent the growth of spoilage microorganisms on the belt surfaces. The additive - either HabaGuard or HyGuard depending on market location - is compounded together with the thermoplastic layers in fabric conveyor belts, or in link belts it is injection moulded throughout the entire module.
Habasit still emphasises the importance of proper cleaning procedures. And this is a message echoed by CRC Industries, whose Ambersil brand of cleaning and degreasing products is used across the food industry. All the products in its range - including Amberclens, Amberklene, Ambergrease and Aquasafe - have received NSF sanitation registration, ensuring they comply with the latest regulations for use on food processing equipment.
As CRC says, by using registered products there is a little less pressure on the maintenance engineer, who is probably the one person in the factory that really does take responsibility for all its conveyors. FM
- Belt Technologies Europe 0191 415 3010
- Bitterling 0870 4289 113
- Crafty Tech 01844 296161
- CRC Industries 01278 727272
- Habasit 0041 61 71515 15
- Isoma 01283 550787
- Sandvik 0049 711 5105 148
- Siegling 0845 330 7110
- Starfrost 01502 562206